Chain Tensioner

#1
Hi there,
Any ideas on a chain tensioner for a doodlebug? Did the stock one have a spring? If not, how does it tighten the chain when needed? Maybe it didn't?
I'm wondering what people are using out there.
Thank you!
-Bill
 

DaddyJohn

Well-Known Member
#2
It would be a roller solidly mounted through a slot on the lower frame rail. It's adjusted forward and backward in the slot via a threaded adjuster.

 

DaddyJohn

Well-Known Member
#4
The roller probably doesn’t have a spacer inside it between the inner races of the bearings. Without it, tightening will side-load the bearing races and bind them up.
 
#5
I bought it from OldMiniBikes warehouse. I was thinking the issue is that I need to find a spacer or washer that is small enough to not come in contact with the whole bearing when it gets tightened.
 
#7
TGM skateboards in Michigan has a 4 dollar spacer kit + ship, that includes 4 longer spacers & 8 thin min. diameter washers.

The bearings on your tensioner are the same size as on skateboards ect.

The stock MM & Doodle bug ect. tensioners do ''not'' really have long enough spacers in them normally anyway,, which can put the bearings in a bind when tightened up.
The min. dia. washers in the TGM kit also just contact the inner races. of the ''outboard'' side of the bearings,, so the bearings won't potentially get pinched with the frame side spacer, & lock washer & ''or'' lock nut.

They work great, & I have them on all the bikes. ;)

I
 
#8
TGM skateboards in Michigan has a 4 dollar spacer kit + ship, that includes 4 longer spacers & 8 thin min. diameter washers.

The bearings on your tensioner are the same size as on skateboards ect.

The stock MM & Doodle bug ect. tensioners do ''not'' really have long enough spacers in them normally anyway,, which can put the bearings in a bind when tightened up.
The min. dia. washers in the TGM kit also just contact the inner races. of the ''outboard'' side of the bearings,, so the bearings won't potentially get pinched with the frame side spacer, & lock washer & ''or'' lock nut.

They work great, & I have them on all the bikes. ;)

I
Wow, great info!!
I think the spacer I would need would measure 5/16 inside diameter and 7/16 outside diameter. Do you know if the spacers in the kit match that?
Thank you!!
-Bill
 
#9
Wow, great info!!
I think the spacer I would need would measure 5/16 inside diameter and 7/16 outside diameter. Do you know if the spacers in the kit match that?
Thank you!!
-Bill
They will work just fine.
O.D. on them is actually around 3/8, so they will match the inner races better anyway. ;)
 
#10
I put one on my Hiawatha mini bike that is off of a Suzuki motor cross bike that uses a free floating sprocket gear and a strong spring.
It keeps a constant pressure on the drive chain and "flexes" as the load from the engine is sent to the rear tire.
 
#17
I cut a piece of 1/4" X 1" aluminum flat bar and drilled 3 holes in it. The tension roller is the stock one and the I reused the stock spacers. I can measure it if you want the dimensions.
I got it. I’m assuming you put a washer or something between the bar and the frame on the bottom hole to allow it to swing more easily
 

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